Threshold voltage bin calibration at memory device power up

ABSTRACT

An example method of threshold voltage offset calibration at memory device power up comprises: identifying a set of memory pages that have been programmed within a time window; determining, for each voltage offset bin of a plurality of voltage offset bins, a corresponding value of a data state metric produced by a memory access operation with respect to a memory page of the set of memory pages, wherein the memory access operation utilizes a voltage offset associated with the voltage offset bin; identifying a subset of the plurality of voltage offset bins, such that memory access operations performed using the corresponding voltage offsets produced respective values of the data state metric that satisfy a predefined quality criterion; selecting, among the subset of the plurality of voltage offset bins, a voltage offset bin that is associated with the lowest voltage offset; and associating the set of memory pages with the selected voltage offset bin.

TECHNICAL FIELD

This application claims the benefit of U.S. Provisional Pat. ApplicationNo. 63/312,349, filed Feb. 21, 2022, the entirety of which isincorporated herein by reference.

TECHNICAL FIELD

Embodiments of the disclosure relate generally to memory sub-systems,and more specifically, relate to threshold voltage offset calibration atmemory device power up.

BACKGROUND

A memory sub-system can include one or more memory devices that storedata. The memory devices can be, for example, non-volatile memorydevices and volatile memory devices. In general, a host system canutilize a memory sub-system to store data at the memory devices and toretrieve data from the memory devices.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will be understood more fully from the detaileddescription given below and from the accompanying drawings of variousembodiments of the disclosure.

FIG. 1 illustrates an example computing system that includes a memorysub-system in accordance with some embodiments of the presentdisclosure.

FIG. 2 depicts an example graph illustrating the dependency of thethreshold voltage offset on the time after program (i.e., the period oftime elapsed since the block had been programmed, in accordance withsome embodiments of the present disclosure.

FIG. 3 schematically illustrates a set of predefined threshold voltageoffset bins, in accordance with embodiments of the present disclosure.

FIG. 4 schematically illustrates selecting block families forcalibration, in accordance with embodiments of the present disclosure.

FIG. 5 schematically illustrates example metadata maintained by thememory sub-system controller for associating blocks and/or partitionswith block families, in accordance with embodiments of the presentdisclosure.

FIG. 6 is a flow diagram of an example method of calibrating thresholdvoltage offset bins at memory device power up in accordance with someembodiments of the present disclosure.

FIG. 7 is a block diagram of an example computer system in whichembodiments of the present disclosure may operate.

DETAILED DESCRIPTION

Aspects of the present disclosure are directed to threshold voltage bincalibration at memory device power up. A memory sub-system can be astorage device, a memory module, or a hybrid of a storage device andmemory module. Examples of storage devices and memory modules aredescribed below in conjunction with FIG. 1 . In general, a host systemcan utilize a memory sub-system that includes one or more components,such as memory devices that store data. The host system can provide datato be stored at the memory sub-system and can request data to beretrieved from the memory sub-system.

A memory sub-system can include high density non-volatile memory deviceswhere retention of data is desired when no power is supplied to thememory device. One example of non-volatile memory devices is anegative-and (NAND) memory device. Other examples of non-volatile memorydevices are described below in conjunction with FIG. 1 . A non-volatilememory device is a package of one or more dies. Each die can include twoor more planes, such that each plane carries a matrix of memory cellsformed onto a silicon wafer and joined by conductors referred to aswordlines and bitlines, such that a wordline joins multiple memory cellsforming a row of the matric of memory cells, while a bitline joinsmultiple memory cells forming a column of the matric of memory cells.Depending on the cell type, each memory cell can store one or more bitsof binary information, and has various logic states that correlate tothe number of bits being stored. The logic states can be represented bybinary values, such as “0” and “1”, or combinations of such values. Aset of memory cells referred to as a memory page can be programmedtogether in a single operation, e.g., by selecting consecutive bitlines.

Data operations can be performed by the memory sub-system. The dataoperations can be host-initiated operations. For example, the hostsystem can initiate a data operation (e.g., write, read, erase, etc.) ona memory sub-system. The host system can send access requests (e.g.,write command, read command) to the memory sub-system, such as to storedata on a memory device at the memory sub-system and to read data fromthe memory device on the memory sub-system. The data to be read orwritten, as specified by a host request, is hereinafter referred to as“host data.” A host request can include logical address information(e.g., logical block address (LBA), namespace) for the host data, whichis the location the host system associates with the host data. Thelogical address information (e.g., LBA, namespace) can be part ofmetadata for the host data. Metadata can also include error handlingdata (e.g., ECC codeword, parity code), data version (e.g. used todistinguish age of data written), valid bitmap (which LBAs or logicaltransfer units contain valid data), etc.

A memory device includes multiple memory cells, each of which can store,depending on the memory cell type, one or more bits of information. Amemory cell can be programmed (written to) by applying a certain voltageto the memory cell, which results in an electric charge being held bythe memory cell, thus allowing modulation of the voltage distributionsproduced by the memory cell. Moreover, precisely controlling the amountof the electric charge stored by the memory cell allows to establishmultiple threshold voltage levels corresponding to different logicallevels, thus effectively allowing a single memory cell to store multiplebits of information: a memory cell operated with 2n different thresholdvoltage levels is capable of storing n bits of information. Thus, theread operation can be performed by comparing the measured voltageexhibited by the memory cell to one or more reference voltage levels inorder to distinguish between two logical levels for single-level cellsand between multiple logical levels for multi-level cells.

Due to the phenomenon known as slow charge loss (SCL), the thresholdvoltage of a memory cell changes in time as the electric charge of thecell is degrading, which is referred to as “temporal voltage shift”(since the degrading electric charge causes the voltage distributions toshift along the voltage axis towards lower voltage levels). Thethreshold voltage is changing rapidly at first (immediately after thememory cell was programmed), and then slows down in an approximatelylogarithmic linear fashion with respect to the time elapsed since thecell programming event. Accordingly, failure to mitigate the temporalvoltage shift caused by the slow charge loss can result in the increasedbit error rate in read operations.

Some memory sub-systems mitigate the temporal voltage shift by employingblock family based error avoidance strategies. The temporal voltageshift is selectively tracked for programmed blocks grouped by blockfamilies, and appropriate voltage offsets, which are based on blockaffiliation with a certain block family, are applied to the base readlevels in order to perform read operations. “Block family” herein shallrefer to a set of blocks that have been programmed within a specifiedtime window and a specified temperature window. Since the time elapsedafter programming and temperature are the main factors affecting thetemporal voltage shift, all blocks and/or partitions within a singleblock family are presumed to exhibit similar distributions of thresholdvoltages in memory cells, and thus would require the same voltageoffsets to be applied to the base read levels for read operations. “Baseread level” herein shall refer to the initial threshold voltage levelexhibited by the memory cell immediately after programming. In someimplementations, base read levels can be stored in the metadata of thememory device.

Block families can be created asynchronously with respect to blockprogramming events. In an illustrative example, a new block family canbe created whenever a specified period of time (e.g., a predeterminednumber of minutes) has elapsed since creation of the last block familyor the reference temperature of memory cells has changed by more than aspecified threshold value. The memory sub-system controller can maintainan identifier of the active block family, which is associated with oneor more blocks as they are being programmed.

The memory sub-system controller can periodically perform a calibrationprocess (also referred to as a calibration scan) in order to evaluate adata state metric (e.g., a bit error rate) and associate each blockfamily with one of predefined threshold voltage offset bins (referred toas bins), which is in turn associated with the voltage offset to beapplied for read operations. The bins can be numbered from 0 to 7 (e.g.,bin 0 - bin 7), and each bin can be associated with a voltage offset tobe applied to a base read level for read operations. The associations ofblock families with bins (e.g., bins 0-7) can be stored in respectivemetadata tables maintained by the memory sub-system controller. However,once the memory device is disconnected from the power supply (e.g., by agraceful or asynchronous power loss event), the SCL may be significantduring the time the memory device is disconnected from the power supplythus most if not all block families will need to be recalibrated usingthe calibration process. However, the memory sub-system may be unable toprecisely determine the duration of the power loss state (e.g., using aninternal clock), thus performing the calibration process and maintainingthe respective metadata table may not be successful. As a result most ifnot all of the block families may be improperly associated with thewrong bins.

Some memory sub-systems mitigate the incorrect association of the blockfamilies to the bins by performing calibration scans to update thepermanent metadata table based on a chosen data state metric. However, acalibration scan after power up can be extremely time consuming becausemost if not all block families need to be recalibrated. Accordingly,rather than performing calibration scans, a memory sub-system can read apage of each block family with a voltage offset associated with each binand measure a corresponding value of a chosen data state metric. Then,the memory sub-system associates each block family with the bin whosevoltage offset resulted in the lowest value of the data state metric(i.e., a quick calibration procedure). While the quick calibrationprocedure is much faster than the calibration scan, it may result inassigning certain block families to incorrect bins. For example, a blockfamily may be assigned to a higher bin (e.g., bin 4) rather than a lowerbin (e.g., bin 3) which is the correct bin.

Furthermore, a memory sub-system may incorrectly assign block familiesto the wrong bins, due to only reading a single page of each blockfamily, which can provide a limited comprehension of the data statemetrics associated with the overall block family. Additionally, in someembodiments, based on varying widths of the voltage distributionsproduced by the memory cell, a voltage distribution may be wide enoughto support multiple bins that would produce an acceptable data statemetric. Accordingly, the bin associated with the data state metric withthe lowest value may in fact be applying larger voltage offsets to thebase read levels than what is required to compensate for the SCL,thereby resulting in increased data state metrics. Thus, as the datastate metric associated with subsequent read operations increases andexceeds a threshold criterion (e.g., BEC or RBER is above a thresholdvalue) indicating a high error rate associated with data stored at theblock, the memory sub-system performs media management operations (e.g.,a folding operation) to relocate the data stored at the wordline orentire block to a new block of the memory sub-system.

Aspects of the present disclosure address the above and otherdeficiencies by identifying a subset of voltage offset bins such thatany of the identified voltage offset bins, if utilized for a readoperation with respect to a page of a chosen block family, would resultin a value of a chosen data state metric falling within an acceptablerange. Then, the voltage offset bin having the smallest thresholdvoltage offset is selected among the identified subset of voltage offsetbins, and the selected voltage offset bin is associated with the blockfamily.

Advantages of the present disclosure include, but are not limited to,more accurately and efficiently assigning the block family to thecorrect bin, thereby, reducing the number of folding operations on thememory device and improving performance of the memory device.

FIG. 1 illustrates an example computing system 100 that includes amemory sub-system 110 in accordance with some embodiments of the presentdisclosure. The memory sub-system 110 can include media, such as one ormore volatile memory devices (e.g., memory device 140), one or morenon-volatile memory devices (e.g., memory device 130), or a combinationof such.

A memory sub-system 110 can be a storage device, a memory module, or ahybrid of a storage device and memory module. Examples of a storagedevice include a solid-state drive (SSD), a flash drive, a universalserial bus (USB) flash drive, an embedded Multi-Media Controller (eMMC)drive, a Universal Flash Storage (UFS) drive, a secure digital (SD) anda hard disk drive (HDD). Examples of memory modules include a dualin-line memory module (DIMM), a small outline DIMM (SO-DIMM), andvarious types of non-volatile dual in-line memory module (NVDIMM).

The computing system 100 can be a computing device such as a desktopcomputer, laptop computer, network server, mobile device, a vehicle(e.g., airplane, drone, train, automobile, or other conveyance),Internet of Things (IoT) enabled device, embedded computer (e.g., oneincluded in a vehicle, industrial equipment, or a networked commercialdevice), or such computing device that includes memory and a processingdevice.

The computing system 100 can include a host system 120 that is coupledto one or more memory sub-systems 110. In some embodiments, the hostsystem 120 is coupled to different types of memory sub-system 110. FIG.1 illustrates one example of a host system 120 coupled to one memorysub-system 110. As used herein, “coupled to” or “coupled with” generallyrefers to a connection between components, which can be an indirectcommunicative connection or direct communicative connection (e.g.,without intervening components), whether wired or wireless, includingconnections such as electrical, optical, magnetic, etc.

The host system 120 can include a processor chipset and a software stackexecuted by the processor chipset. The processor chipset can include oneor more cores, one or more caches, a memory controller (e.g., NVDIMMcontroller), and a storage protocol controller (e.g., PCIe controller,SATA controller). The host system 120 uses the memory sub-system 110,for example, to write data to the memory sub-system 110 and read datafrom the memory sub-system 110.

The host system 120 can be coupled to the memory sub-system 110 via aphysical host interface. Examples of a physical host interface include,but are not limited to, a serial advanced technology attachment (SATA)interface, a peripheral component interconnect express (PCIe) interface,universal serial bus (USB) interface, Fibre Channel, Serial AttachedSCSI (SAS), a double data rate (DDR) memory bus, Small Computer SystemInterface (SCSI), a dual in-line memory module (DIMM) interface (e.g.,DIMM socket interface that supports Double Data Rate (DDR)), etc. Thephysical host interface can be used to transmit data between the hostsystem 120 and the memory sub-system 110. The host system 120 canfurther utilize an NVM Express (NVMe) interface to access components(e.g., memory devices 130) when the memory sub-system 110 is coupledwith the host system 120 by the physical host interface (e.g., PCIebus). The physical host interface can provide an interface for passingcontrol, address, data, and other signals between the memory sub-system110 and the host system 120. FIG. 1 illustrates a memory sub-system 110as an example. In general, the host system 120 can access multiplememory sub-systems via a same communication connection, multipleseparate communication connections, and/or a combination ofcommunication connections.

The memory devices 130,140 can include any combination of the differenttypes of non-volatile memory devices and/or volatile memory devices. Thevolatile memory devices (e.g., memory device 140) can be, but are notlimited to, random access memory (RAM), such as dynamic random accessmemory (DRAM) and synchronous dynamic random access memory (SDRAM).

Some examples of non-volatile memory devices (e.g., memory device 130)include negative-and (NAND) type flash memory and write-in-place memory,such as a three-dimensional cross-point (“3D cross-point”) memorydevice, which is a cross-point array of non-volatile memory cells. Across-point array of non-volatile memory can perform bit storage basedon a change of bulk resistance, in conjunction with a stackablecross-gridded data access array. Additionally, in contrast to manyflash-based memories, cross-point non-volatile memory can perform awrite in-place operation, where a non-volatile memory cell can beprogrammed without the non-volatile memory cell being previously erased.NAND type flash memory includes, for example, two-dimensional NAND (2DNAND) and three-dimensional NAND (3D NAND).

Each of the memory devices 130 can include one or more arrays of memorycells, such as memory array 137. One type of memory cell, for example,single level cells (SLC) can store one bit per cell. Other types ofmemory cells, such as multi-level cells (MLCs), triple level cells(TLCs), quad-level cells (QLCs), and penta-level cells (PLCs) can storemultiple bits per cell. In some embodiments, each of the memory devices130 can include one or more arrays of memory cells such as SLCs, MLCs,TLCs, QLCs, or any combination of such. In some embodiments, aparticular memory device can include an SLC portion, and an MLC portion,a TLC portion, a QLC portion, or a PLC portion of memory cells. Thememory cells of the memory devices 130 can be grouped as pages that canrefer to a logical unit of the memory device used to store data. Withsome types of memory (e.g., NAND), pages can be grouped to form blocks.

Although non-volatile memory components such as 3D cross-point array ofnon-volatile memory cells and NAND type flash memory (e.g., 2D NAND, 3DNAND) are described, the memory device 130 can be based on any othertype of non-volatile memory, such as read-only memory (ROM), phasechange memory (PCM), self-selecting memory, other chalcogenide basedmemories, ferroelectric transistor random-access memory (FeTRAM),ferroelectric random access memory (FeRAM), magneto random access memory(MRAM), Spin Transfer Torque (STT)-MRAM, conductive bridging RAM(CBRAM), resistive random access memory (RRAM), oxide based RRAM(OxRAM), negative-or (NOR) flash memory, and electrically erasableprogrammable read-only memory (EEPROM).

A memory sub-system controller 115 (or controller 115 for simplicity)can communicate with the memory devices 130 to perform operations suchas reading data, writing data, or erasing data at the memory devices 130and other such operations. The memory sub-system controller 115 caninclude hardware such as one or more integrated circuits and/or discretecomponents, a buffer memory, or a combination thereof. The hardware caninclude a digital circuitry with dedicated (i.e., hard-coded) logic toperform the operations described herein. The memory sub-systemcontroller 115 can be a microcontroller, special purpose logic circuitry(e.g., a field programmable gate array (FPGA), an application specificintegrated circuit (ASIC), etc.), or other suitable processor.

The memory sub-system controller 115 can be a processing device, whichincludes one or more processors (e.g., processor 117), configured toexecute instructions stored in a local memory 119. In the illustratedexample, the local memory 119 of the memory sub-system controller 115includes an embedded memory configured to store instructions forperforming various processes, operations, logic flows, and routines thatcontrol operation of the memory sub-system 110, including handlingcommunications between the memory sub-system 110 and the host system120.

In some embodiments, the local memory 119 can include memory registersstoring memory pointers, fetched data, etc. The local memory 119 canalso include read-only memory (ROM) for storing micro-code. While theexample memory sub-system 110 in FIG. 1 has been illustrated asincluding the memory sub-system controller 115, in another embodiment ofthe present disclosure, a memory sub-system 110 does not include amemory sub-system controller 115, and can instead rely upon externalcontrol (e.g., provided by an external host, or by a processor orcontroller separate from the memory sub-system).

In general, the memory sub-system controller 115 can receive commands oroperations from the host system 120 and can convert the commands oroperations into instructions or appropriate commands to achieve thedesired access to the memory devices 130. The memory sub-systemcontroller 115 can be responsible for other operations such as wearleveling operations, garbage collection operations, error detection anderror-correcting code (ECC) operations, encryption operations, cachingoperations, and address translations between a logical address (e.g.,logical block address (LBA), namespace) and a physical address (e.g.,physical block address) that are associated with the memory devices 130.The memory sub-system controller 115 can further include host interfacecircuitry to communicate with the host system 120 via the physical hostinterface. The host interface circuitry can convert the commandsreceived from the host system into command instructions to access thememory devices 130 as well as convert responses associated with thememory devices 130 into information for the host system 120.

The memory sub-system 110 can also include additional circuitry orcomponents that are not illustrated. In some embodiments, the memorysub-system 110 can include a cache or buffer (e.g., DRAM) and addresscircuitry (e.g., a row decoder and a column decoder) that can receive anaddress from the memory sub-system controller 115 and decode the addressto access the memory devices 130.

In some embodiments, the memory devices 130 include local mediacontroller 132 that operate in conjunction with memory sub-systemcontroller 115 to execute operations on one or more memory cells of thememory devices 130. An external controller (e.g., memory sub-systemcontroller 115) can externally manage the memory device 130 (e.g.,perform media management operations on the memory device 130). In someembodiments, a memory device 130 is a managed memory device, which is araw memory device combined with a local controller (e.g., localcontroller 132) for media management within the same memory devicepackage. An example of a managed memory device is a managed NAND (MNAND)device.

In one embodiment, the memory sub-system 110 includes a storage chargeloss management (SCLM) component 113. Upon detecting a power up event,the SCLM component 113 can performs 113 a voltage bin calibration. In anillustrative example, the SCLM component 113 may identity a subset ofvoltage offset bins that would produce satisfactory values of a chosendata state metric when utilized for performing read operations for oneor more pages of a given block family (or other defined set of pages).The data state metric can be represented by, e.g., the raw bit errorrate. The satisfactory value of the data state metric can be verified bya predetermined quality criterion (e.g., the value of the data statemetric not exceeding a predefined threshold). Upon identifying a subsetof voltage offset bins producing satisfactory values of the chosen datastate metric when utilized for performing read operations for one ormore pages of a given block family (or other defined set of pages), theSCLM component 113 may select, among the identified subset of voltageoffset bins, a voltage offset bin that has the lowest voltage offset.The selected offset bin can then be associated with the block family (orother defined set of pages).

Should the SCLM component 113 be unable to identify at least one voltageoffset bin that would produce a satisfactory value of the chosen datastate metric, the SCLM component 113 may select, among the plurality ofdefined voltage offset bins, the voltage offset bin which, when utilizedfor performing read operations for one or more pages of a given blockfamily (or other defined set of pages), produced the optimal (i.e., theminimum or maximum) value of the data state metric, as compared to othervoltage offset bins. The selected offset bin can then be associated withthe block family (or other defined set of pages).

Further details regarding the operations of the SCLM component 113 aredescribed below.

FIG. 2 depicts an example graph 200 illustrating the dependency of thethreshold voltage offset 210 on the time after program 220 (i.e., theperiod of time elapsed since the block had been programmed. Asschematically illustrated by FIG. 2 , blocks of the memory device aregrouped into block families 230A-230N, such that each block familyincludes one or more blocks that have been programmed within a specifiedtime window and a specified temperature window. As noted herein above,since the time elapsed after programming and temperature are the mainfactors affecting the temporal voltage shift, all blocks and/orpartitions within a single block family 210 are presumed to exhibitsimilar distributions of threshold voltages in memory cells, and thuswould require the same voltage offsets for read operations.

Block families can be created asynchronously with respect to blockprogramming events. In an illustrative example, the memory sub-systemcontroller 115 of FIG. 1 can create a new block family whenever aspecified period of time (e.g., a predetermined number of minutes) haselapsed since creation of the last block family or whenever thereference temperature of memory cells, which is updated at specifiedtime intervals, has changed by more than a specified threshold valuesince creation of the current block family.

A newly created block family can be associated with bin 0. Then, thememory sub-system controller can periodically perform a calibrationprocess in order to associate each die of every block family with one ofthe predefines threshold voltage offset bins (bins 0-7 in theillustrative example of FIG. 2 ), which is in turn associated with thevoltage offset to be applied for read operations. The associations ofblocks with block families and block families and dies with thresholdvoltage offset bins can be stored in respective metadata tablesmaintained by the memory sub-system controller.

FIG. 3 schematically illustrates a set of predefined threshold voltageoffset bins (bin 0 to bin 9), in accordance with embodiments of thepresent disclosure. As schematically illustrated by FIG. 3 , thethreshold voltage offset graph can be subdivided into multiple thresholdvoltage offset bins, such that each bin corresponds to a predeterminedrange of threshold voltage offsets. While the illustrative example ofFIG. 4 defines ten bins, in other implementations, various other numbersof bins can be employed (e.g., 64 bins). Based on a periodicallyperformed calibration process, the memory sub-system controllerassociates each die of every block family with a threshold voltageoffset bin, which defines a set of threshold voltage offsets to beapplied to the base voltage read level in order to perform readoperations, as described in more detail herein below.

FIG. 4 schematically illustrates selecting block families forcalibration, in accordance with embodiments of the present disclosure.As schematically illustrated by FIG. 4 , the memory sub-systemcontroller can limit the calibration operations to the oldest blockfamily in each bin (e.g., block family 410 in bin 0 and block family 420in bin 1), since it is the oldest block family that will, due to theslow charge loss, migrate to the next bin before any other block familyof the current bin.

FIG. 5 schematically illustrates example metadata maintained by thememory sub-system controller for associating blocks and/or partitionswith block families, in accordance with embodiments of the presentdisclosure. As schematically illustrated by FIG. 5 , the memorysub-system controller can maintain the superblock table 510, the familytable 520, and the offset table 530.

Each record of the superblock table 510 specifies the block familyassociated with the specified superblock and partition combination. Insome implementations, the superblock table records can further includetime and temperature values associated with the specified superblock andpartition combination.

The family table 520 is indexed by the block family number, such thateach record of the family table 520 specifies, for the block familyreferenced by the index of the record, a set of threshold voltage offsetbins associated with respective dies of the block family. In otherwords, each record of the family table 520 includes a vector, eachelement of which specifies the threshold voltage offset bin associatedwith the die referenced by the index of the vector element. Thethreshold voltage offset bins to be associated with the block familydies can be determined by the calibration process, as described in moredetail herein above.

Finally, the offset table 530 is indexed by the bin number. Each recordof the offset table 530 specifies a set of threshold voltage offsets(e.g., for TLC, MLC, and/or SLC) associated with threshold voltageoffset bin.

The metadata tables 510-530 can be stored on one or more memory devices130 of FIG. 1 . In some implementations, at least part of the metadatatables can be cached in the local memory 119 of the memory sub-systemcontroller 115 of FIG. 1 .

In operation, upon receiving a read command, the memory sub-systemcontroller determines the physical address corresponding to the logicalblock address (LBA) specified by the read command. Components of thephysical address, such as the physical block number and the dieidentifier, are utilized for performing the metadata table walk: first,the superblock table 510 is used to identify the block family identifiercorresponding to the physical block number; then, the block familyidentifier is used as the index to the family table 520 in order todetermine the threshold voltage offset bin associated with the blockfamily and the die; finally, the identified threshold voltage offset binis used as the index to the offset table 530 in order to determine thethreshold voltage offset corresponding to the bin. The memory sub-systemcontroller can then additively apply the identified threshold voltageoffset to the base voltage read level in order to perform the requestedread operation.

In the illustrative example of FIG. 5 , the superblock table 510 mapspartition 0 of the superblock 0 to block family 4, which is utilized asthe index to the family table 520 in order to determine that die 0 ismapped to bin 3. The latter value is used as the index to the offsettable in order to determine the threshold voltage offset values for bin3.

FIG. 6 is a flow diagram of an example method 600 of calibratingthreshold voltage offset bins at memory device power-up in accordancewith some embodiments of the present disclosure. The method 600 can beperformed by processing logic that can include hardware (e.g.,processing device, circuitry, dedicated logic, programmable logic,microcode, hardware of a device, integrated circuit, etc.), software(e.g., instructions run or executed on a processing device), or acombination thereof. In some embodiments, the method 600 is performed bySCLM component 113 of FIG. 1 . Although shown in a particular sequenceor order, unless otherwise specified, the order of the processes can bemodified. Thus, the illustrated embodiments should be understood only asexamples, and the illustrated processes can be performed in a differentorder, and some processes can be performed in parallel. Additionally,one or more processes can be omitted in various embodiments. Thus, notall processes are required in every embodiment. Other process flows arepossible.

At operation 610, the processing logic identifies a set of memory pagesthat have been programmed within a certain time window. In someembodiments, the set of memory pages may be a block family. As describedpreviously, block families can be created asynchronously with respect toblock programming events, such as, creating a new block family whenevera specified period of time (e.g., a predetermined number of minutes) haselapsed since creation of the last block family.

At operation 620, the processing logic traverses the set of voltageoffset bins. For each voltage offset bin, the processing logic performs,with respect to one or more memory pages of the chosen set of memorypages, a memory access operation (e.g., a read operation) using thevoltage offset specified by the currently selected voltage offset bin.Performing the memory access operation may involve additively applying,to a predefined base voltage level, a voltage offset associated with achosen voltage offset bin, and utilizing the resulting updated voltagelevel for performing the memory access operation. For each memory accessoperation, a corresponding data state metric (e.g., the raw bit errorrate (RBER) is determined.

At operation 630, the processing logic tests, by a chosen qualitycriterion, each data state metric value produced by operation 620, inorder to identify a subset of voltage offset bins that producedsatisfactory values of the data state metric (i.e., data state metricvalues satisfying the chosen quality criterion). In an illustrativeexample, the quality criterion may be satisfied if the value of the datastate metric does not exceed a predefined threshold. In anotherillustrative example, the quality criterion may be satisfied if thevalue of the data state metric does not fall below a predefinedthreshold. In an illustrative example, the data state metric is providedby the bit error rate, and the quality criterion would be satisfied ifthe value of the data state metric does not exceed a predefinedthreshold.

At operation 640, the processing logic selects, among the identifiedsubset of voltage offset bins, a voltage offset bin that is associatedwith the lowest voltage offset.

In some embodiments, responsive to determining that no memory accessoperation produced a satisfactory value of the data state metric, theprocessing logic may select, among the plurality of voltage offset bins,the voltage offset bin that produced the optimal (e.g., the minimum orthe maximum) value of the data state metric. In an illustrative example,the data state metric is provided by the bit error rate, and the voltageoffset bin resulting in the minimum bit error rate would be selected.

At operation 650, the processing logic associates the set of memorypages with the selected voltage offset bin. The association of the setof memory pages with the selected voltage offset bin may be stored inone or more metadata tables (e.g., table 510 of FIG. 5 ), and may beutilized for performing subsequent memory access operations.

FIG. 7 illustrates an example machine of a computer system 800 withinwhich a set of instructions, for causing the machine to perform any oneor more of the methodologies discussed herein, can be executed. In someembodiments, the computer system 800 can correspond to a host system(e.g., the host system 120 of FIG. 1 ) that includes, is coupled to, orutilizes a memory sub-system (e.g., the memory sub-system 110 of FIG. 1) or can be used to perform the operations of a controller (e.g., toexecute an operating system to perform operations corresponding to theSCLM component 113 of FIG. 1 ). In alternative embodiments, the machinecan be connected (e.g., networked) to other machines in a LAN, anintranet, an extranet, and/or the Internet. The machine can operate inthe capacity of a server or a client machine in client-server networkenvironment, as a peer machine in a peer-to-peer (or distributed)network environment, or as a server or a client machine in a cloudcomputing infrastructure or environment.

The machine can be a personal computer (PC), a tablet PC, a set-top box(STB), a Personal Digital Assistant (PDA), a cellular telephone, a webappliance, a server, a network router, a switch or bridge, or anymachine capable of executing a set of instructions (sequential orotherwise) that specify actions to be taken by that machine. Further,while a single machine is illustrated, the term “machine” shall also betaken to include any collection of machines that individually or jointlyexecute a set (or multiple sets) of instructions to perform any one ormore of the methodologies discussed herein.

The example computer system 800 includes a processing device 802, a mainmemory 804 (e.g., read-only memory (ROM), flash memory, dynamic randomaccess memory (DRAM) such as synchronous DRAM (SDRAM) or Rambus DRAM(RDRAM), etc.), a static memory 806 (e.g., flash memory, static randomaccess memory (SRAM), etc.), and a data storage system 818, whichcommunicate with each other via a bus 830.

Processing device 802 represents one or more general-purpose processingdevices such as a microprocessor, a central processing unit, or thelike. More particularly, the processing device can be a complexinstruction set computing (CISC) microprocessor, reduced instruction setcomputing (RISC) microprocessor, very long instruction word (VLIW)microprocessor, or a processor implementing other instruction sets, orprocessors implementing a combination of instruction sets. Processingdevice 802 can also be one or more special-purpose processing devicessuch as an application specific integrated circuit (ASIC), a fieldprogrammable gate array (FPGA), a digital signal processor (DSP),network processor, or the like. The processing device 802 is configuredto execute instructions 826 for performing the operations and stepsdiscussed herein. The computer system 800 can further include a networkinterface device 808 to communicate over the network 820.

The data storage system 818 can include a machine-readable storagemedium 824 (also known as a computer-readable medium) on which is storedone or more sets of instructions 826 or software embodying any one ormore of the methodologies or functions described herein. Theinstructions 826 can also reside, completely or at least partially,within the main memory 804 and/or within the processing device 802during execution thereof by the computer system 800, the main memory 804and the processing device 802 also constituting machine-readable storagemedia. The machine-readable storage medium 824, data storage system 818,and/or main memory 804 can correspond to the memory sub-system 110 ofFIG. 1 .

In one embodiment, the instructions 826 include instructions toimplement functionality corresponding to SCLM component 113 of FIG. 1 ).While the machine-readable storage medium 824 is shown in an exampleembodiment to be a single medium, the term “machine-readable storagemedium” should be taken to include a single medium or multiple mediathat store the one or more sets of instructions. The term“machine-readable storage medium” shall also be taken to include anymedium that is capable of storing or encoding a set of instructions forexecution by the machine and that cause the machine to perform any oneor more of the methodologies of the present disclosure. The term“machine-readable storage medium” shall accordingly be taken to include,but not be limited to, solid-state memories, optical media, and magneticmedia.

Some portions of the preceding detailed descriptions have been presentedin terms of algorithms and symbolic representations of operations ondata bits within a computer memory. These algorithmic descriptions andrepresentations are the ways used by those skilled in the dataprocessing arts to most effectively convey the substance of their workto others skilled in the art. An algorithm is here, and generally,conceived to be a self-consistent sequence of operations leading to adesired result. The operations are those requiring physicalmanipulations of physical quantities. Usually, though not necessarily,these quantities take the form of electrical or magnetic signals capableof being stored, combined, compared, and otherwise manipulated. It hasproven convenient at times, principally for reasons of common usage, torefer to these signals as bits, values, elements, symbols, characters,terms, numbers, or the like.

It should be borne in mind, however, that all of these and similar termsare to be associated with the appropriate physical quantities and aremerely convenient labels applied to these quantities. The presentdisclosure can refer to the action and processes of a computer system,or similar electronic computing device, that manipulates and transformsdata represented as physical (electronic) quantities within the computersystem’s registers and memories into other data similarly represented asphysical quantities within the computer system memories or registers orother such information storage systems.

The present disclosure also relates to an apparatus for performing theoperations herein. This apparatus can be specially constructed for theintended purposes, or it can include a general purpose computerselectively activated or reconfigured by a computer program stored inthe computer. Such a computer program can be stored in a computerreadable storage medium, such as, but not limited to, any type of diskincluding floppy disks, optical disks, CD-ROMs, and magnetic-opticaldisks, read-only memories (ROMs), random access memories (RAMs), EPROMs,EEPROMs, magnetic or optical cards, or any type of media suitable forstoring electronic instructions, each coupled to a computer system bus.

The algorithms and displays presented herein are not inherently relatedto any particular computer or other apparatus. Various general purposesystems can be used with programs in accordance with the teachingsherein, or it can prove convenient to construct a more specializedapparatus to perform the method. The structure for a variety of thesesystems will appear as set forth in the description below. In addition,the present disclosure is not described with reference to any particularprogramming language. It will be appreciated that a variety ofprogramming languages can be used to implement the teachings of thedisclosure as described herein.

The present disclosure can be provided as a computer program product, orsoftware, that can include a machine-readable medium having storedthereon instructions, which can be used to program a computer system (orother electronic devices) to perform a process according to the presentdisclosure. A machine-readable medium includes any mechanism for storinginformation in a form readable by a machine (e.g., a computer). In someembodiments, a machine-readable (e.g., computer-readable) mediumincludes a machine (e.g., a computer) readable storage medium such as aread only memory (“ROM”), random access memory (“RAM”), magnetic diskstorage media, optical storage media, flash memory components, etc.

In the foregoing specification, embodiments of the disclosure have beendescribed with reference to specific example embodiments thereof. Itwill be evident that various modifications can be made thereto withoutdeparting from the broader spirit and scope of embodiments of thedisclosure as set forth in the following claims. The specification anddrawings are, accordingly, to be regarded in an illustrative senserather than a restrictive sense.

What is claimed is:
 1. A method comprising: identifying, by a processing device, a set of memory pages that have been programmed within a time window; determining, for each voltage offset bin of a plurality of voltage offset bins, a corresponding value of a data state metric produced by a memory access operation with respect to a memory page of the set of memory pages, wherein the memory access operation utilizes a voltage offset associated with the voltage offset bin; identifying a subset of the plurality of voltage offset bins, such that memory access operations performed using the corresponding voltage offsets produced respective values of the data state metric that satisfy a predefined quality criterion; selecting, among the subset of the plurality of voltage offset bins, a voltage offset bin that is associated with the lowest voltage offset; and associating the set of memory pages with the selected voltage offset bin.
 2. The method of claim 1, further comprising: responsive to determining that the memory access operations performed using the corresponding voltage offsets failed to produce a value of the data state metric satisfying the predefined quality criterion, selecting, among the plurality of voltage offset bins, a voltage offset bin that produced an optimal value of the data state metric, wherein the optimal value if represented by one of: a minimum value of the data state metric or a maximum value of the data state metric.
 3. The method of claim 2, further comprising: associating the set of memory pages with the selected voltage offset bin.
 4. The method of claim 1, wherein the set of memory pages is a block family.
 5. The method of claim 1, wherein determining the value of the data state metric further comprises: determining an updated voltage level by additively applying, to a base voltage level, the voltage offset associated with the respective voltage offset bin; performing the memory access operation using the updated voltage level; and determining the value of the data state metric produced the memory access operation.
 6. The method of claim 1, wherein the memory access operation is a read operation.
 7. The method of claim 1, wherein the data state metric is a bit error rate.
 8. A system comprising: a memory device; and a processing device coupled to the memory device, the processing device to perform operations comprising: identifying a set of memory pages that have been programmed within a time window; determining, for each voltage offset bin of a plurality of voltage offset bins, a corresponding value of a data state metric produced by a memory access operation with respect to a memory page of the set of memory pages, wherein the memory access operation utilizes a voltage offset associated with the voltage offset bin; identifying a subset of the plurality of voltage offset bins, such that memory access operations performed using the corresponding voltage offsets produced respective values of the data state metric that satisfy a predefined quality criterion; selecting, among the subset of the plurality of voltage offset bins, a voltage offset bin that is associated with the lowest voltage offset; and associating the set of memory pages with the selected voltage offset bin.
 9. The system of claim 8, further comprising: responsive to determining that the memory access operations performed using the corresponding voltage offsets failed to produce a value of the data state metric satisfying the predefined quality criterion, selecting, among the plurality of voltage offset bins, a voltage offset bin that produced an optimal value of the data state metric, wherein the optimal value if represented by one of: a minimum value of the data state metric or a maximum value of the data state metric.
 10. The system of claim 9, wherein the operations further comprise: associating the set of memory pages with the selected voltage offset bin.
 11. The system of claim 8, wherein the set of memory pages is a block family.
 12. The system of claim 8, wherein determining the value of the data state metric further comprises: determining an updated voltage level by additively applying, to a base voltage level, the voltage offset associated with the respective voltage offset bin; performing the memory access operation using the updated voltage level; and determining the value of the data state metric produced the memory access operation.
 13. The system of claim 8, wherein the memory access operation is a read operation.
 14. The system of claim 8, wherein the data state metric is a bit error rate.
 15. A non-transitory computer-readable storage medium comprising instructions that, when executed by a processing device, cause the processing device to perform operations comprising: identifying a set of memory pages that have been programmed within a time window; determining, for each voltage offset bin of a plurality of voltage offset bins, a corresponding value of a data state metric produced by a memory access operation with respect to a memory page of the set of memory pages, wherein the memory access operation utilizes a voltage offset associated with the voltage offset bin; identifying a subset of the plurality of voltage offset bins, such that memory access operations performed using the corresponding voltage offsets produced respective values of the data state metric that satisfy a predefined quality criterion; selecting, among the subset of the plurality of voltage offset bins, a voltage offset bin that is associated with the lowest voltage offset; and associating the set of memory pages with the selected voltage offset bin.
 16. The non-transitory computer-readable storage medium of claim 15, further comprising: responsive to determining that the memory access operations performed using the corresponding voltage offsets failed to produce a value of the data state metric satisfying the predefined quality criterion, selecting, among the plurality of voltage offset bins, a voltage offset bin that produced an optimal value of the data state metric, wherein the optimal value if represented by one of: a minimum value of the data state metric or a maximum value of the data state metric; and associating the set of memory pages with the selected voltage offset bin.
 17. The non-transitory computer-readable storage medium of claim 15, wherein the set of memory pages is a block family.
 18. The non-transitory computer-readable storage medium of claim 15, wherein determining the value of the data state metric further comprises: determining an updated voltage level by additively applying, to a base voltage level, the voltage offset associated with the respective voltage offset bin; performing the memory access operation using the updated voltage level; and determining the value of the data state metric produced the memory access operation.
 19. The non-transitory computer-readable storage medium of claim 15, wherein the memory access operation is a read operation.
 20. The non-transitory computer-readable storage medium of claim 15, wherein the data state metric is a bit error rate. 